Image-capturing devices include cameras, portable handheld electronic devices, and other electronic devices. The images captured by image-capturing devices may be compromised based on motion of the image-capturing devices. For example, vibration, camera shake, or rotation of the camera may blur images.
One prior approach uses software that compares similar portions of different frames and adjusts the output image based on the comparison. This approach typically compensates for translational motion, but fails to compensate for rotational motion.
Some image-capturing devices may use what could be referred to as a rolling shutter as a method of image acquisition in which each frame is recorded not from a snapshot of an entire frame at a single point in time, but rather by scanning across the frame, one line at a time, either vertically or horizontally. In other words, not all parts of the image are recorded at exactly the same time, even though the whole frame is displayed at the same time during playback. At least some CMOS image sensors have a rolling shutter. Rolling shutter produces predictable distortions of fast-moving objects or when the sensor captures rapid flashes of light. This method is implemented by rolling (moving) the shutter across the exposable image area instead of exposing the image area all at the same time. Rolling shutters can cause such effects as skew and wobble. Skews occur when the image bends diagonally in one direction or another as the camera or subject moves from one side to another, exposing different parts of the image at different times. Wobble is most common in hand-held shots at telephoto settings and most extreme in cases when the camera is vibrating due to being attached to a moving vehicle. The rolling shutter causes the image to wobble unnaturally and bizarrely. This is often called the jello effect.
Prior approaches for stabilizing images captured with a rolling shutter may include post-processing techniques. These techniques typically compensate for translational motion, but fail to compensate for rotational motion.